A woman using a Grand Central Terminal stairwell fell and broke her ankle last year because a spooky advertisement for the series startled her, a new lawsuit charges.

Ajanaffy Njewadda and her husband, a former Gambian ambassador, are suing the MTA and the cable network, accusing them of placing the ad in a dangerous spot for pedestrians.

“Our contention is that the ad shouldn’t have been there,” the couple’s lawyer, Rehan Nazrali, told DNAinfo New York. “The combined nature of the ad along with its placement poses a hazard to people on the steps.”

The poster's closeup of “Dexter” star Michael C. Hall with cellophane covering his face was “shocking and menacing," the lawsuit says. Hall played a mild-mannered crime lab technician for the Miami Metro Police Department who moonlights as a serial killer and uses the plastic wrap on his victims.

The poster promoting the eighth and final season of the show covered the side of every step of a stairwell that led to the shuttle train at Grand Central. It was only viewable to pedestrians ascending the stairwell.

The lawsuit, filed last week in Bronx Supreme Court, says that on June 20, 2013, Njewadda was walking down the steps after going through a subway turnstile.

As she descended the stairwell, she grew concerned after she lost track of her husband, Sheik Ahmad Tejan Wadda, who got stuck at the turnstile.

When Njewadda turned around to walk up the stairwell to search for her husband, the poster frightened her, causing her to lose her balance and tumble down the steps, the lawsuit says.

Njewadda, who has a home in the Concourse section of the Bronx and in Gambia, broke her ankle and suffered a concussion. She also had to see a psychiatrist — like Dexter does in the show’s eighth season.

“She was having nightmares about it,” Nazrali said.

The lawyer said that before he filed the lawsuit, he contacted Showtime about a settlement. But the network’s insurer refused to make a deal, Nazrali said, claiming there was nothing wrong with the sign because New Yorkers don’t scare easily.

“I remember that the conversation we had was that a Manhattan jury will not see this poster and placement as dangerous or scary. Essentially, New York jurors are sensible and that I may be laughed out of court,” Nazrali said. “I said. 'Let’s see.'”

A Showtime spokeswoman said the company could not comment because it had not yet received the lawsuit. An MTA spokeswoman declined to comment on pending litigation.

Nazrali said the MTA is at fault for placing the ad in the wrong location.

Her husband got stuck in the turnstile and she got scared by an ad on a staircase. Send these 2 dumb fucks back to Africa. Should probably send their lawyer back with them for thinking this lawsuit was a good idea.